الفهرس 
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Abstract
Pseudomonas infection was found to be a serious problem because it causes high mortality in newly hatched chickens and death of embryos at later stage. Pseudomonas infections of birds are of great importance because epidemics may spread rapidly through poultry flocks causing mortality in all ages.
In this investigation, the bacteriological examination of 460 chicks representing 46 farms from freshly dead and live ailing chicks revealed that the prevalence of the positive cases was 183 chicks (39.78%) and the prevalence of positive farms from different governorates was 32 from 46 (69.6%), while the bacteriological examination of 600 dead in shell chicks representing 20 hatcheries revealed that the 126 (21%) dead in shell chicks were positive for P. aeruginosa while 15 from 20 hatcheries were positive with a percentage of 75%.
On the other hand, The results of the sensetivity test showed that all isolates were resistant to Spectinomycin, Naldixic acid and Cephradine with percentage 100%. The most effective antibiotics were Levofloxacine (100%) followed by Imipenem (87.5%), Amikacine (71.87) and Enrofloxacine (59.3%). On Studying Antibiotic resistance to different antibiotics among P. aeruginosa isolated from broiler chicks in accordance to their importance to human health showed complete resistance towards cefotaxime , and nalidixic acid (with percentages 100%for each) followed by amoxicillin , colistine sulphate , gentamycin and tobramycin ,danofloxacin , enrofloxacin and Imipenem (93.75, 65.625, 62.5, 56.25 53.125 , 40.6, 25 and 12.5% respectively) which all classified according to WHO as a critical Important antibiotics for human use (Category I). Also, complete resistance was recorded among highly important antibiotics (Category II) as cefradine, and high resistance rates among sulfamethxazole/ trimethoprim, doxycycline, florfenicol, (96.88, 90.63 % respectively). Complete resistance was found in all isolates towards spectinomycin which included as an important drug for human medicine (Category III). The results of antibiotic resistant pattern of the isolated P. aeruginosa from chicks revealed that all the isolates were multidrug resistant to at least 1 agent in at least 5 antimicrobial categories used recording a multidrug resistant index ranged of 0.4 to 0.8 according to the multi-drug resistance index formula.
The results of the antimicrobial sensetivity test of pseudomonas strains isolated from dead in shell embryos revealed that All isolates were resistant to Spectinomycin, , Cephradine Doxycycline and Cefotaxime with percentage 100% The most effective antibiotics were Imipenem (93.33)followed by Levofloxacin (86.67), Colistin sulphate (86.67) and Enrofloxacine (80%). Results of antibiotic resistance to different antibiotics among P. aeruginosa isolated from dead in shell chicks in accordance to their importance to human health revealed complete resistance towards cefotaxime , amoxicillin and nalidixic acid (with percentages 100%for each) followed by amikacin, gentamycin ,tobramycin and Imipenem ( 40, 33.3 , 20 and 6.6% respectively) which all classified according to WHO as a critical Important antibiotics for human use (Category I). Also, complete resistance were recorded among highly important antibiotics (Category II) as cefradine, Florfenicol, Sulphamethoxazole /Trimethoprim and Doxycycline (with percentages 100%for each). Complete resistance was found in all isolates towards spectinomycin which included as an important drug for human medicine (Category III).
The results of antibiotic resistant pattern of P. aeruginosa isolated from dead in shell chicks revealed that all the isolates were multidrug resistant to at least 1 agent in at least 5 antimicrobial categories used recording a multidrug resistant index ranged of 0.43 to 0.68 according to the multi-drug resistance index formula.
Studying some virulence characters of P. aeruginosa isolates revealed revealed that strong biofilm formation was detected in 37.5 % and 26.66% of isolates recovered from chicks and dead in shell chicks respectively using tube method on the other hand weak biofilm formation was detected in a percentages of 18.75 % and 20% of isolates recovered from chicks and dead shell respectively. Gelatine hydrolysis activity showed that gelatine hydrolysis activity was positive (Partial or total liquefaction of the inoculated tube) in 25 (78.12 %) isolates recovered from chicks, while was positive in 9 isolates recovered from dead in shell chicks by percentage of 60 %.
The β-hemolysis activity was found in 21 from a total of 32 P. aeruginosa isolates recovered from chicks by percentage of 67.2 % while detected in 6 isolates from 15 isolates recovered from dead in shell chicks by percentage of 40% . On the other hand, α haemolysis reached 34.4% and 46.6 from isolates recovered from chicks and dead in shell respectively. P. aeruginosa isolates were 100% positive to Lecithinase production activity of isolates recovered from both chicks dead in shell chicks. Casein hydrolysis activity of P. aeruginosa illustrated that P. aeruginosa isolates were 100% positive to casein hydrolysis activity of isolates recovered from both chicks dead in shell chicks.
By serotyping of selected 20 P. aeruginosa isolated from chicks and dead in shell chicks the results revealed two poly valent type 2& 3 by percent of 45% and 55 % respectively also the serotype 2 typed to 3 groupes of mono valent types J,M and K by percent of 66.6%,22.2 % and 11.1 respectively while the poly valent type 3 typed into 5 type ,D,G,N,F and E by percent of 18.2%, 18.2%,45.5 %, 9.1 % and 9.1% respectively
The Detection of virulence genes revealed that Twenty six isolates of P.aeruginosa (18 from dead in chick isolated strains and 7 from chicks isolated strains and reference strain ATCC9027) were examined by PCR for detection of opr L , nan1, exoS , lasB, toxA and bla TEM . The results revealed that opr L found in all isolates by percent 100% , toxA found in an incidence of 92.3%, exoS(88.5%), and lasB (96.2%) while the lowest incidence was nan1 by percentage of (50%). The correlation between the results of some virulence tests and the presence of some virulence genes in the selected 18 isolates recovered from chicks. Las B gene present in all isolates showed strong biofilm formation and all isolates showed positive gelatin hydrolysis and all isolate showed β hemolysis on blood agar by incidence of 100 % while nan1 gene was present in 83.3% of isolates showed strong biofilm formation and 73.3% in isolates showed positive gelatin hydrolysis and 71.4% in the isolate showed β hemolysis.